It has been proposed to provide armored military vehicles with "explosive" active armor which is activated by the vehicle's defensive aids sensor suite on detection of an incoming missile. The detonation of a charge at or near the vehicle's outer surface produces a shower of fragments which, if correctly timed, will damage the incoming missile before it reaches the vehicle. If however the charge is detonated accidentally, the vehicle is likely to be damaged unnecessarily, and there is a risk of injury to any personnel in the vicinity of the vehicle.
Missiles and other ordnance may be directed towards a target using laser guidance, "laser guided ordnance" being the generic name for this family of weapon systems. These weapons have a laser seeking sensor device which is sensitive to laser radiation scattered by the target. The laser radiation is directed at the target from a distant laser designator which may be on the vehicle launching the laser guided ordnance, on a separate vehicle or on the ground, with a means of communicating with the weapon launching system to synchronize the attack. The illuminating laser radiation is formed into a narrow beam so that only the target is illuminated, and is in the form of a precisely timed pulse train. The laser seeking sensor or "seeker" is generally sensitive only to the laser wavelength in use and only reacts to laser pulse trains with the correct timing characteristics, and may use further discrimination techniques to minimize the susceptibility of the system to a range of decoy techniques.
There are two broad classes of laser guided ordnance. One class is bombs and missiles of the 225-900 kg (500-2000 lb) class, designed for use against large heavy fixed installations. The other class is laser guided missiles, typically used for anti-tank applications. For both classes of ordnance, a target is illuminated by a laser designator. Both types of ordnance are directed towards the scattered reflected laser radiation. Bombs follow a ballistic trajectory and will generally dive onto the target. The large warhead will detonate on or after impact and may cause damage even with a near miss. To protect a large installation against a bomb it is necessary to decoy the seeker sufficiently to cause the bomb to fall many meters from the point illuminated by the laser designator. On the other hand, laser guided anti-tank missiles generally follow a flat trajectory and will only damage the target seriously if they achieve a direct hit. To protect a vehicle, particularly a tank or other armored vehicle, against laser guided anti-tank missiles, it is therefore only necessary to cause the missile to deviate sufficiently to prevent a direct hit.
Existing laser repeater decoys illuminate a point near the target with a pulse train from a laser which is triggered by receipt of incoming laser pulses. The repeater pulse is arranged to go out very quickly after the received pulse so that timing circuits in the seeker are unable to discriminate against the decoy from the pulse interval. To minimize the time of flight difference between the real and decoy lasers, the decoy is usually thrown forward of the target towards the incoming threat. The laser energy of the decoy as seen by the seeker also needs to be stronger than the return from the real designating beam to ensure the seeker accepts the decoy rather than the real designator. Finally, if the decoy is placed too far from the real target, the seeker may not see it or may be able to determine that the decoy is not the correct target. In a prepared position the geometry and energy levels can be determined and a suitable decoy location selected. However, in the case of a mobile vehicle this is much more difficult, particularly since the vehicle will often position itself behind ground or vegetation cover which would block or attenuate the decoy signal to a missile seeker.
It is among the objects of embodiments of the present invention to provide an arrangement for protecting vehicles against incoming projectiles which does not require such precise timing as the existing active armor countermeasures described above, and which will not present a danger to personnel in the event of accidental activation.
It is among the objects of further embodiments of the present invention to provide an arrangement for implementing a laser decoy which will be effective in protecting vehicles against laser anti-tank missiles.